Dynamic light scattering (DLS), which is also known as quasi-elastic light scattering (QELS), is an optical analysis technique that is well known in the art. An optical source such as laser light is focused into the sample. Light scatters when it hits particles suspended in the fluid, such as platelets suspended in solution. The scattered light is collected by light collectors disposed at specific angles relative to the incident light. As is known in the art, the scattered light fluctuates due to Brownian motion of the particles in solution. Using algorithms that are known in the art, these fluctuations of scattered light are then correlated to the particles' mean size and shape which are expressed in terms of hydrodynamic radius.
To perform dynamic light scattering on a fluid sample, the fluid sample is contained within a translucent container (e.g. a capillary or cuvette) that is, in turn, held by a sample holder, also known as a capillary holder or cuvette holder.
A number of sample holders and DLS-type apparatuses having sample-holding compartments are known in the art, for example the Coulter N4 Plus™ from Beckman Coulter, Inc. of Fullerton, Calif. and the DynaPro Titan™ from Wyatt Technology Corporation of Santa Barbara, Calif.
Some sample-holding devices are described in U.S. Patent Application 2005/0094127 (O'Mahony et al.) entitled CUVETTE APPARATUS AND SYSTEM FOR MEASURING OPTICAL PROPERTIES OF A LIQUID SUCH AS BLOOD; U.S. Pat. No. 6,016,193 (Freeman et al.) entitled CUVETTE HOLDER FOR COAGULATION ASSAY TEST; U.S. Pat. No. 6,249,344 (Virag) entitled METHOD AND APPARATUS FOR SEDIMENTATION AND OPTICAL EXAMINATION OF PARTICLES SUSPENDED IN A FLUID, FURTHER A CUVETTE FOR ACCOMPLISHING SAID METHOD; U.S. Design Pat. D442,287 (Pogorzelski) entitled CUVETTE HOLDER; U.S. Design Pat. D271,335 (Simons) entitled CUVETTE HOLDER; U.S. Pat. No. 4,208,127 (Hufenreuter) entitled CUVETTE HOLDER; U.S. Pat. No. 6,488,892 (Burton et al.) entitled SAMPLE-HOLDING DEVICES AND SYSTEMS; U.S. Pat. No. 6,399,026 (Karrai) entitled SAMPLE HOLDER APPARATUS; U.S. Pat. No. 6,266,139 (Mannhardt) entitled CAPILLARY TUBE HOLDER; U.S. Pat. No. 4,278,437 (Haggar) entitled FLUID SPECIMEN HOLDER FOR BIOLOGICAL FLUID TESTING; U.S. Pat. No. 6,239,875 (Verheijen) entitled PHOTOMETRIC MEASURING SYSTEM AND A HOLDER FOR SUCH A SYSTEM; U.S. Pat. No. 6,055,050 (Skiffington) entitled PHOTOMETER AND TEST SAMPLE HOLDER FOR USE THEREIN, METHOD AND SYSTEM; U.S. Patent Application 2004/0233423 (Nakayama et al.) entitled SAMPLE HOLDER FOR SPECTRUM MEASUREMENT AND SPECTROPHOTOMETER; U.S. Pat. No. 5,900,132 (Keenan et al.) entitled CAPILLARY HOLDER; U.S. Pat. No. 5,733,507 (Zakim) entitled BIOLOGICAL CELL SAMPLE HOLDER FOR USE IN INFRARED AND/OR RAMAN SPECTROSCOPY ANALYSIS HOLDER; U.S. Pat. No. 6,188,474 (Dussault et al.) entitled OPTICAL SPECTROSCOPY SAMPLE CELL; U.S. Pat. No. 5,674,457 (Williamson et al.) entitled CAPILLARY MICROCUVETTE; Canadian Patent 1,247,399 (Wyatt et al.) entitled SAMPLE CELL FOR LIGHT SCATTERING MEASUREMENTS; Canadian Patent 1,242,595 (Phillips et al.) entitled SAMPLE CELL FOR LIGHT SCATTERING MEASUREMENTS; and U.S. Pat. No. 5,530,540 (Wyatt et al.) entitled LIGHT SCATTERING MEASUREMENT CELL FOR VERY SMALL VOLUMES.
However, to the extent of Applicant's knowledge, each of these prior-art sample holders is only designed to hold a specific type of container (i.e. either a round capillary or a square cuvette) and furthermore is only designed to only hold a container of a specific size or of a very limited size range. Accordingly, it would be highly desirable to provide a sample holder that redressed this deficiency.
Moreover, many of these prior-art sample holders include means for heating and/or cooling the fluid sample in order to collect DLS measurements at different temperatures. However, these prior-art temperature-controlled sample holders are not designed for efficient and uniform heat transfer because they must provide optical access for both the incident light and the scattered light. In other words, heating or cooling elements are located inefficiently (such as beneath the container) in order to ensure that there is adequate optical access. The prior-art designs have in general failed to optimize both optical access and heat transfer. It would therefore be highly desirable to provide a sample holder that enables efficient and uniform heat transfer without unduly compromising optical access to the sample.